Transducer with shock absorbing mounting



1970 H. s. KNOWLES 3,534,183

TRANSDUCER WITH SHOCK ABSORBING MOUNTING Original Filed May 25. 1966 I N VE NTOR. HUGH SHALER KNOWLES BY Jnagwm Jafi/W ATTORNEY United States Patent Continuation of application Ser. No. 552,958, May 25, 1966. This application June 26, 1969, Ser. No. 841,671 Int. Cl. H041 1/28 U.S. Cl. 179--180 8 Claims ABSTRACT OF THE DISCLOSURE A transducer adapted to be mounted in a housing and comprising a case and a diaphragm mounted in the case. An aperture in the case provides an opening for sound to be transmitted between the diaphragm and the exterior of the case. A resilient sound duct having one side open is adhesively secured to the case and the open side of the duct communicates with the aperture. The duct in cooperation with the case defines a sound-conducting path. A tubular duct connects with the sound duct and is adapted for engagement with the transducer housing to cooperate with the sound duct to provide shock absorbing features for said transducer, and the sound duct has a vibration dampening protuberance.

This is a continuation of application Ser. No. 552,958, filed May 25, 1966, now abandoned.

This invention relates to an insolator for mounting on the external surface of a transducer case and more particularly for very small microphone or receiver transducer cases. The instant isolator not only provides shock and vibration protection for transducers but also a sound conducting path externally of the case. This application is a continuation-in-part of applicants copending United States patent application Ser. No. 204,942, filed June 25, 1962, now Pat. No. 3,257,516, issued on June 21, 1966.

It is recognized that in the design and manufacture of a hearing aid which includes one or more transducers, it is necessary to provide protection of the transducer from damage by excessive shock loadings and undesired vibration. Most of the damage which ordinarily occurs to a hearing aid is caused by dropping the hearing aid onto a hard surface, such as, a tile floor in a bathroom. The shock loads which occur upon dropping a hearing aid onto a hard surface often severely damage the transducer. In one series of experiments made with a transducer, it was found that dropping a transducer from a height of one meter onto a hard surface caused a deceleration upon impact of approximately 3000 g. and a high value of 15,000 g. was attained in one instance. In order to avoid generation of extraneous sounds in the hearing aid, it is particularly desirable to mount a transducer in the hearing aid so that the transducer is not affected by external vibrations.

One of the important considerations in the design and manufacture of a hearing aid is the cosmetic effect of the hearing aid on a patient. In order to improve the cosmetic effect of the hearing aid, it is desirable to make the hearing aid as small as possible so that the parts of the hearing aid do not detract from the appearance of the patient. It is apparent that the parts of the hearing aid must be minute to conserve space in the hearing aid.

Considering the various arts involved in the design and manufacture of a hearing aid, it is evident that it is more economical and efficient for a hearing aid manufacturer to use certain commercially available component parts in the design of a given hearing aid and to purchase these component parts for inclusion in the final product. One of these component parts, which is normally purchased by a hearing aid manufacturer, is the 3,534,183 Patented Oct. 13, 1970 ice transducer. Transducers, which serve as microphones and receivers, are usually manufactured by a specialist in the design and production thereof. For economical production of transducers, the transducer manufacturer must produce only certain standard models for sale to all hearing aid manufacturers. However, a given hearing aid manufacturer customarily has its own individual design for a hearing aid and a standard model transducer of transducer manufacturer must fit into the overall design.

One problem which often plagues both hearing aid manufacturers and transducer manufacturers is the positioning of the sound opening in the transducer case. The transducer manufacturer usually positions the sound opening to attain the utmost efliciency of the transducer. However, the hearing aid manufacturer usually desires to have the sound opening located in a particular position so that it may adapt itself to its particular hearing aid construction, which is usually different than that of every other hearing aid manufacturer. So that a transducer manufacturers standard model may adapt itself to various designs, it is desirable to provide a conventional means for transmitting the sound from the sound opening in a transducer case to a second location. This requires a sound duct of some type, and of course, sound ducts require space. It is one of the principal objects of the present invention to provide an isolator for use with a transducer which isolator is highly efiicient in that it performs three important functions, namely; it acts as a vibration mounting, it acts as a shock absorber, and it acts as a sound duct. By combining three functions into a single part, the overall size of a hearing aid may be materially reduced thereby providing an improved construction for a hearing aid.

'It is a further object of the instant invention to provide an isolator which may be readily and simply applied to a transducer case to direct sound along a desired path.

It is a still further object of the herein disclosed invention to provide an improved isolator construction which is inexpensive to manufacture and is an eflicient shock absorber for a transducer.

Other objects and uses of this invention will become readily apparent to those skilled in the art upon a perusal of the following specification in light of the accompanying drawing in which:

FIG. 1 is a perspective view of a transducer with a pair of isolators each embodying the instant invention mounted thereon;

FIG. 2 is a cross-sectional view through a transducer with a pair of isolators mounted thereon shown in FIG. 1 and taken on line 2-2 of said figure;

FIG. 3 is a plan view of a transducer with an isolator shown mounted on one corner and a second isolator shown in dotted form mounted on a diametrically opposed corner,

FIG. 4 is a plan view of a transducer case with an isolator mounted thereon showing the isolator positioned on the corner of the transducer;

FIG. 5 is a plan view of an isolator embodying the herein disclosed invention; and

FIG. 6 is an end view of the isolator shown in FIG. 5.

Referring now to the drawing, a conventional transducer generally indicated by numeral 10 is shown therein. The details of construction of the instant transducer are disclosed in detail in United States Letters Patent No. 3,111,563. A pair of isolators 12 and 112, embodying the subject invention are shown mounted on the transducer 10; however, the isolators are operative with any transducer.

The transducer 10 as may be best seen in FIG. 2 generally includes, a case, which includes a cup 14, a lid 16, and a closure 18, is positioned in cup 14. A diaphragm 20 is mounted on the closure 18. Positioned in cup 14 is a magnet stack 22 with an armature reed 24 connected to the magnet stack. A coil 26 is mounted in the cup with a portionof the armature reed extending through the coil. A drive pin 28 connects the armature reed with the diaphragm 20. In this instance, the lid 16 of the case has a sound aperture 30 positioned adjacent to one corner.

The isolator 12 in this instance is a molded unitary rubber part having substantial resilience. The isolator generally consists of a boot 32, which is adhesively secured to the case and communicates with sound aperture 30 to act as a resilient sound duct, and a circular tubular duct 34 which is formed integral with the boot. The boot 32 includes a pair of C-shaped side walls 36 and 38. Connecting the side walls 36 and 38 is an outer Wall 40 with which is integrally formed the tubular duct 34. An upper end wall 42 is formed integral with the ends of the side walls and the outer wall and is adhesively secured to the case. A lower end wall 44 is formed integral with opposite ends of the side walls and the outer wall. An upper protuberance 46 is formed integral with the outer wall 40 and a like lower protuberance 48 is formed integral with the lower end wall 44 as may be best seen in FIG. 2. The construction of isolator 112 is identical to isolator 12; however, isolator 112 does not communicate with a sound aperture so that it acts as a shock absorber, vibration dampener and stabilizer. Both isolators 12 and 112 are fixed to the case by a suitable adhesive applied to the surfaces of the isolator in contact with the case so that the isolator 12 is sealed to the case thereby forming a sealed sound path between the boot and the case which sound path extends into the duct.

The transducer 10, as is conventional, is mounted in a conventional hearing aid housing 50 a portion of which housing is shown in FIG. 2. The housing has a cavity 52 which receives the transducer and isolators 12 and 112. The protuberances engage the housing and the tubular ducts are positioned in the housing. Duct 34 of isolator 12 communicates with a conventional sound duct in the hearing aid which sound duct is not shown herein.

As was mentioned above, the boot 32 has an open side so that when the isolator is secured to the case of the transducer the case forms one side of a sound path with the boot which sound path extends into the tubular duct 34, so that sound may be transmitted along the sound path to the interior of case through aperture 40. The operation of the sound on the diaphragm 20 is described in detail in the aforementioned Pat. No.

The armature reed 24 has a node of vibration adjacent to one end as is fully described in the aforementioned Pat. 3,111,563. The protuberances 46 and 48 and a line defining the node of vibration define a plane 54. It may be thus appreciated that any vibration of the housing is primarily dampened by protuberances 46 and 48, which are on the plane of the node of vibration, so that little or no vibration is transmitted to the transducer.

The instant isolator operates in the following manner. As was described above, the protuberances provide vibration dampening. It may be appreciated that these protuberances are small and dampen vibration before it is transmitted to the transducer. Furthermore, the boot 32 also serves to absorb some vibration. However, when a hearing aid is dropped, and there is shock loading on the transducer, the small protuberances do not offer substantial absorbance of shock loading, but rather the C- shaped end walls 36 and 38 are deformed to absorb any shock loading on the transducer. It should be further noted that since the tubular duct 34 is held in the housing 50, the tubular duct cooperates with the boot to absorb some of the shock loading on the transducer. The other isolator 112 provides also a shock absorber for the transducer 10 in the same manner as that described in isolator 12.

It may be seen that by utilizing the isolator 12 which also serves as a sound conduit, the sound may be carried to any desired point. For instance in FIG. 4, it is shown that the sound may be carried off at the corner of the case. In FIG. 3, an isolator is shown at one corner and another isolator in dotted form at the diametrically opposed corner, whereby the transducer is, in effect, rotated degrees. Thus, the manunfacturer of a hearing aid is not limited in positioning a transducer to one position because of the location of the sound aperture. By utilizing the isolator of the subject invention, the manufacturers of hearing aids and of transducers are given a greater latitude in design.

It should also be noted that though two isolators are shown in cooperation to provide a shock absorber for a transducer, it is possible to use only one isolator, that is, the single isolator which is connected to the sound aperture 30. When the isolator 112 is eliminated, the transducer is suspended in the cavity 52 in a cantilever fashion and the protuberances 46 and 48 play a more important part in dampening vibration to the transducer. It is apparent that any shock loading is then taken up only by isolator 12 as described in detail above.

Although a particular transducer construction has been shown and described herein, it is readily apparent that various transducers may be utilized with the subject isolator. It is to be expressly understood that the instant invention is in no way limited by the type of transducer shown herein. It is, therefore, understood that those skilled in the art may make various modifications and changes in the instant invention without departing from the spirit thereof. The instant invention is in no way limited by the disclosure contained herein but limited only by the appended claims.

What is claimed is:

1. In a transducer adapted to be mounted in a housing and having a case and a diaphragm mounted in said case, said case having an aperture to provide an opening for SOund to be transmitted between one side of the diaphragm and the exterior of the case, the improvement comprising a resilient sound duct having one side open, said sound duct secured at its open side to the case and communicating with said aperture to define a sound-conducting path, a portion of said sound duct extending adjacent to a portion of the transducer case to provide a portion of the sound-conducting path, a tubular duct communicating with said sound duct to provide a sound conducting path, said tubular duct being adapted for engagement with the housing for said transducer to cooperate with said sound duct to provide a shock absorber for said transducer.

2. In a transducer as described in claim 1 having a resilient tubular duct formed integral with the resilient sound duct and communicating with the sound duct to provide a sound path, said tubuplar duct being adapted for engagement with a housing whereby said tubular duct cooperates with said sound duct under a shock loading to provide a shock absorbing means for said transducer.

3. A transducer as described in claim 1, wherein a protuberance is positioned on said resilient sound duct and is adapted for engagement with the housing for the transducer, whereby said protuberance provides a vibration-dampening means for the transducer.

4. In a transducer as defined in claim 1 having a protuberance formed integral with the sound duct and adapted for engagement with a Wall of a housing for the transducer, whereby the protuberance provides means for vibration-dampening of the transducer.

5. In a transducer having a magnet; a coil; an armature reed magnetically connected to the magnet and the coil; said armature reed having a mode of vibration defining a substantially straight line; a case enclosing said magnet, the coil and the armature reed; and a diaphragm in said case connected to the armature reed; said case having an aperture to provide an opening for sound to be transmitted between the diaphragm and the exterior of the case; the improvement comprising, a resilient sound duct having one side open, said open side adhesively secured to the case and communicating with the aperture to define a sound-conductive path, a pair of protuberances formed integral with the resilient sound duct and being positioned on opposite sides of the case, said protuberances and the line defined by the node of vibration of the reed defining a single plane, whereby said protuberances provide vibration-dampening means for the transducer, and the sound duct deforms under shock loading to provide shock-absorbing means for said transducer.

6. In a transducer as defined in claim wherein the aperture in said case is positioned in a substantially flat side of the case and a portion of the resilient sound duct is parallel to the side of the case to provide a soundconducting path which is substantially perpendicular to the axis of the aperture.

7. In a transducer as described in claim 5 a tubular duct is formed integral with the sound duct to provide a continuous sound-conducting path in cooperation with the sound duct, said tubular duct is adapted for engagement with the housing for said transducer and cooperates with the sound duct to provide a shock-abrosbing means for the transducer. T

8. In a transducer having a case and a diaphragm in said case, said case having a substantially fiat side and having an aperture in the side to provide an opening for sound to be transmitted between the diaphragm and the exterior of hte case, the improvement comprising, a resilient sound duct having a pair of substantially parallel side walls and an outer Wall formed integral with the side Walls, said resilient sound duct having the ends of the side walls adhesively secured to a portion of the side of the case having the aperture and communicating with the aperture to define a portion of a sound-conducting path, a tubular duct formed integral with the resilient sound duct and defining a second portion of the soundconducting path, said tubular duct being adapted for engagement with a housing for the transducer, whereby the sound duct and the tubular duct are deformed under shock loading to provide shock-absorbing means for said transducer.

References Cited UNITED STATES PATENTS 2,506,981 5/1950 Weaver et a1. 179-107 KATHLEEN CLAFFY, Primary Examiner T. W. BROWN, Assistant Examiner US. Cl. X.R. 179146, 184 

